MySQL sorting group-by results -

MySQL sorting group-by results -

i have next tables structure:

table_1

id title ------------ 155 item1 156 item2 157 item3

table_2

id model ------------ 155 100 156 100 157 200

table_3

id cid ------------ 155 5 156 5 157 5

i want grouping results model (from table_2) and create sure returns highest id (order id descending).

i have tried following, order by clause doesn't seem work:

select a.id, b.model table_1 inner bring together table_2 b on b.id = a.id inner bring together table_3 c on c.id = a.id c.cid = 5 grouping b.model order a.id desc

what doing wrong?

select max(a.id), b.model table_1 inner bring together table_2 b on b.id = a.id inner bring together table_3 c on c.id = a.id c.cid = 5 grouping b.model order max(a.id) desc

demo here: http://sqlfiddle.com/#!9/afb0b/2

the reason works while initial effort did not, field not nowadays in group by clause, or not used in aggregate function (such max), have indeterminate value (ie, mysql engine makes no guarantees value grouping get).

mysql grouping handling

the server free take value each group, unless same, values chosen indeterminate.

in fact, mysql 1 of few (only?) sql databases allow set non aggregated, non grouped field in select clause without erroring.

mysql group-by sql-order-by